1. Field of the Invention
The present invention relates to a medical X-ray imaging detector and a medical X-ray imaging apparatus so as to take out an image such as X-ray transmitted image of entire jaw in the field of dental surgery, oral surgery and otolaryngology.
2. Prior Art
An X-ray imaging detector using highly sensitive CCD (Charge Coupled Device) image sensor as imaging element comparing to a prior film type one recording X-ray transmitted image on an X-ray film has been used.
In a CCD image sensor, an electric charged image obtained by converting X-ray transmitted through an object into visible light by a scintillator is produced on a light receiver, the electric charged image is output in a form of voltage signal after time delay integrated, and finally A/D converted so as to be taken out as electronic image.
When panoramic X-ray imaging is executed for entire jaw, according to basic principle of imaging, transfer speed of electric charged image generated and accumulated on the CCD image sensor is required to be kept at a speed corresponding to rotational speed of a rotary arm in spite of relatively moving the object and the film at a prescribed speed. Such a principle is known as TDI (Time Delay Integration) imaging as shown in JP-A-61-22841, JP-A-2-84942, and JP-Y-4-48169.
In JP-A-11-104127 and JP-A-11-104218, an X-ray imaging detector which can directly take out an X-ray transmitted image as electronic image by incorporating an A/D converter in a CCD image sensor and an improved X-ray imaging apparatus in which such an X-ray imaging detector has compatibility with a conventional film detector so as to be detachable on a detector holder of an X-ray imaging apparatus have been proposed. Both of them have attempted to execute TDI imaging easily.
However, in the above-mentioned prior arts, an X-ray imaging apparatus is provided with a TDI clock generator and so on for executing TDI imaging and a TDI clock generator isn""t provided for an X-ray imaging detector itself. Therefore, a TDI clock generator and so on should be provided for an X-ray imaging apparatus for TDI imaging so that it requires much cost for modifying a conventional film type X-ray imaging apparatus to an X-ray imaging apparatus using a CCD sensor. A technique for achieving TDI imaging at a low cost has been highly desired.
The prior arts have only taught an improved method wherein panoramic imaging producing X-ray transmitted image is produced on X-ray film has been substituted with electronic image, or an X-ray generator and an X-ray detector are moved interposing an object. Such prior art hasn""t shown method wherein imaging time is speeded up and electronic image for adequate diagnosis is obtained.
The advantage of executing panoramic X-ray imaging at high speed is in that image out of focus caused by moving of an object is solved by shortening imaging time. Moreover, X-ray amount radiated on the object can be restrained and it is useful for reducing X-ray exposed dose amount.
The present invention has been made to solve the above problems. The first object of the invention is to provide an X-ray imaging detector wherein TDI (Time Delay Integration) imaging using an imaging element such as CCD can be executed even if an X-ray imaging apparatus isn""t provided with a TDI clock generator.
The second object of the invention is to provide an X-ray imaging detector for executing high speed imaging, which is an ultimate object wherein suitable method hasn""t been proposed in conventional TDI imaging using an imaging element such as CCD for obtaining X-ray image.
The third object of the invention is to provide an X-ray imaging detector which can generate electronic images with different resolutions by altering imaging mode according to diagnostic purposes.
Further object of the invention is to provide an X-ray imaging detector which is user-friendly improved from the view point of user in order to achieve the above-mentioned first to third objects.
Moreover, the other object of the invention is to provide a medical X-ray imaging apparatus which can achieve the above-mentioned objects by itself.
In order to solve the above-mentioned problems, the applicant of the present invention proposes an X-ray imaging detector, an X-ray imaging apparatus having an X-ray imaging detector, and an X-ray imaging apparatus having a function of an X-ray imaging detector by itself.
The present invention proposes an X-ray imaging detector for generating X-ray transmitted image in a form of electric signal for use in an X-ray imaging apparatus in which the X-ray imaging apparatus comprises an X-ray generator and a fixing means for fixedly positioning an object to be examined between the X-ray generator and the X-ray imaging detector mounted thereon, whereby X-ray imaging is performed by moving the X-ray generator and the X-ray imaging detector both interposing the object fixedly positioned by the fixing means while keeping facing each other. The X-ray imaging detector comprises an imaging element for generating electric charged image constituting X-ray transmitted image by detecting X-ray radiated from the X-ray generator and transmitted through the object, a TDI clock generator for generating TDI clock signal, and a TDI clock controller for controlling generating of TDI clock signal from the TDI clock generator based on TDI frequency control data for controlling the frequency of the TDI clock signal and for executing TDI control of the electric charged image generated by the imaging element corresponding to the TDI clock signal.
This X-ray imaging detector itself is provided with the TDI clock generator and the TDI clock controller and is a autonomic type detector of which imaging mode is such that the imaging element can be TDI controlled without receiving supply of TDI clock signal from the X-ray imaging apparatus. Therefore, if the TDI clock generator isn""t provided for the X-ray imaging apparatus, TDI imaging can be achieved so that the above-mentioned first object can be accomplished.
A CCD imaging sensor is preferably used for an imaging element, however, any device can be used if it can execute TDI control.
According to the above-mentioned X-ray imaging detector of the present invention, the TDI clock controller may be provided with a clock control data memory storing the TDI frequency control data.
In such an X-ray imaging detector, the TDI clock controller has the clock control data memory. Therefore, it is convenient that the TDI frequency control data which has been stored by a manufacturer beforehand can be taken out from the memory and TDI imaging can be executed.
According to the above-mentioned X-ray imaging detector of the present invention, the clock control data memory may rewritablly store the TDI frequency control data.
In such an X-ray imaging detector, the clock control data memory is rewritable and the TDI frequency control data can be rewritten by a manufacturer at the time of shipment in order to meet the product specification of the X-ray imaging apparatus. Therefore, it is convenient that appropriate TDI imaging can be executed in compliance with the X-ray imaging apparatus when a manufacturer attaches the X-ray imaging detector on the X-ray imaging apparatus.
The control data memory is preferably constructed with a flash memory and EEPROM. However, any device can be used if stored data is rewritable and is kept even if an electric source is shut off.
According to the above-mentioned X-ray imaging detector of the present invention, the clock control data memory may store plural patterns of the TDI frequency control data.
In such an X-ray imaging detector, such control as enlarged imaging, maxillary antrum imaging, jaw joint imaging and selection of adult or child can be executed by storing plural patterns of TDI frequency control data in case of panoramic imaging using an X-ray imaging apparatus provided with an X-ray imaging detector. It is very convenient and can accomplish the above-mentioned third object.
According to the above-mentioned X-ray imaging detector of the present invention, a selection means for selecting at least one of the plural patterns of TDI frequency control data stored in the clock control data memory may be further provided.
In such an X-ray imaging detector, TDI frequency control data can be selected by the selection means from the memory storing plural patterns of TDI clock signal so that the above-mentioned third object can be accomplished.
A doctor or an operator may use such a selection means corresponding to the signal of the selection means provided for a controller of the X-ray imaging apparatus or such a selection means may be pre-set by a manufacturer before shipment.
According to the above-mentioned X-ray imaging detector of the present invention, the TDI clock controller may be further provided with binning function when the electric charged image generated by the imaging element is TDI controlled.
The binning function means that the electric charged image produced on the imaging element is summed by real-time operation as it is.
In such an X-ray imaging detector, binning can be executed so as to heighten sensitivity of the sensor and the data amount transmitted to an A/D converter is reduced. Therefore, TDI controlled X-ray imaging can be achieved at high speed without replacing with high speed A/D converter and memory amount for processing picture image for X-ray imaging can be reduced so that the above-mentioned second object can be accomplished.
According to the above-mentioned X-ray imaging detector of the present invention, the TDI clock controller may be further provided with function of moving the X-ray generator and the X-ray imaging detector at high speed while keeping facing each other by executing binning function when the electric charged image generated by the imaging element corresponding to the TDI clock signal is TDI controlled.
In such an X-ray imaging detector, the electric charged image is integrated by binning and the electric charged image with enough contrast can be obtained by small amount of X-ray. Utilizing this, the X-ray generator and the X-ray imaging detector are moved at high speed and X-ray is radiated for a short time. Therefore, X-ray imaging can be executed at higher speed and X-ray exposed dose amount of the object can be reduced without changing the X-ray imaging apparatus itself. Furthermore, the problem of picture out of focus caused by movement of the object is resolved so that the above-mentioned second object can be accomplished.
According to the above-mentioned X-ray imaging detector of the present invention, the TDI clock controller may selectively execute at least normal projection mode and high-speed projection mode which is faster than the normal mode when the electric charged image generated by the imaging element may be TDI controlled and in each projection mode frequency of the TDI clock signal and binning data may control elements.
In such an X-ray imaging detector, it is convenient for an operator that normal projection mode and high speed imaging mode can be selectively executed and each imaging mode can be preferably executed because the frequency of the TDI clock signal and binning information are control element.
According to the above-mentioned X-ray imaging detector of the present invention, an imaging element for producing X-ray transmitted image may be a CCD sensor of full frame transfer type.
In such an X-ray imaging detector, FFT (full frame transfer type) CCD censor is used as an imaging element. By using the characteristic of the sensor in which there is no accumulation part and a light receiving part is enlarged that much, it is preferably achieved for a measurement of slow frame rate, for example TDI X-ray imaging of the present invention.
The present invention proposes an X-ray imaging apparatus provided with the above-mentioned X-ray imaging detector.
Such an X-ray imaging apparatus is provided with the above-mentioned detector so that the same effect as the above-mentioned detector can be achieved.
According to the X-ray imaging apparatus of the present invention, the TDI clock signal produced from the TDI clock generator provided for the X-ray imaging detector and movement control signal for moving the X-ray generator and the X-ray imaging detector both interposing the object fixedly positioned by the fixing means while keeping facing each other are varied in synchronizing manner.
In such an X-ray imaging apparatus, the TDI clock signal of the X-ray imaging detector is synchronized with movement control signal of the X-ray imaging apparatus so that X-ray imaging for executing TDI imaging can be preferably accomplished.
According to the X-ray imaging apparatus of the present invention, the X-ray imaging apparatus may be a panoramic X-ray imaging apparatus.
As the X-ray imaging apparatus is constructed as a panoramic imaging apparatus, the effect of the above-mentioned X-ray imaging apparatus can be brought out in case of panoramic imaging.
According to the X-ray imaging apparatus of the present invention, the X-ray imaging apparatus may be a cephalometric X-ray imaging apparatus.
As the X-ray imaging apparatus is constructed as a cephalometric imaging apparatus, the effect of the above-mentioned X-ray imaging apparatus can be brought out in case of cephalometric imaging.
The present invention proposes an X-ray imaging apparatus comprising an X-ray generator, an X-ray imaging detector, and a fixing means for fixedly positioning an object to be examined between the X-ray generator and the X-ray imaging detector mounted thereon, whereby X-ray imaging is performed by moving the X-ray generator and the X-ray imaging detector both interposing the object fixedly positioned by the fixing means while keeping facing each other. The X-ray imaging detector comprises an imaging element for producing electric charged image constituting X-ray transmitted image by detecting X-ray radiated from the X-ray generator and transmitted through the object. The X-ray imaging apparatus comprises a TDI clock generator for generating TDI clock signal, a clock control data memory storing TDI frequency control data for controlling frequency of TDI clock signal generated from the TDI clock generator, and a TDI clock controller for controlling generating of TDI clock signal from the TDI clock generator based on TDI frequency control data for controlling the frequency of the TDI clock signal and for executing TDI control of the electric charged image generated by the imaging element corresponding to the TDI clock signal. The TDI clock controller is further provided with function of moving the X-ray generator and the X-ray imaging detector at high speed while keeping facing each other by executing binning processing when the electric charged image generated by the imaging element corresponding to the TDI clock signal is TDI controlled.
The X-ray imaging apparatus is provided with the above-mentioned TDI clock generator, the above-mentioned TDI clock controller, the above-mentioned clock control data memory at the X-ray imaging apparatus side. And the TDI clock controller can execute high speed imaging using the above-mentioned binning operation. Therefore, if these parts are provided for the X-ray imaging detector, the apparatus can bring out the same effect as the above-mentioned detector so that high speed binning X-ray imaging apparatus of heteronomic type is achieved.
According to the X-ray imaging apparatus of the present invention, the TDI clock controller may selectively execute at least normal projection mode and high-speed projection mode which is faster than the normal mode when the electric charged image generated by the imaging element is TDI controlled and in each projection mode frequency of the TDI clock signal and binning data may be employed as control elements.
Such an X-ray imaging apparatus is provided with the same function of the above-mentioned X-ray imaging detector on the apparatus side so that the same effect of the X-ray imaging detector can be brought out even if such function isn""t provided for the detector side.
According to the X-ray imaging apparatus of the present invention, an imaging element for producing X-ray transmitted image may be a CCD sensor of FFT (full frame transfer) type.
In such an X-ray imaging apparatus imaging element is FFT type CCD sensor like the above-mentioned X-ray imaging detector so that the same effect as the X-ray imaging detector can be achieved.
According to the X-ray imaging apparatus of the present invention, the TDI clock signal generated from the TDI clock generator provided for the X-ray imaging detector and movement control signal for moving the X-ray generator and the X-ray imaging detector both interposing the object fixedly positioned by the fixing means while keeping facing each other may be varied in synchronizing manner.
In such an X-ray imaging apparatus, the TDI clock signal of the X-ray imaging detector is synchronized with the movement control signal of the X-ray imaging apparatus so that TDI X-ray imaging can be preferably achieved.
According to the X-ray imaging apparatus of the present invention, the X-ray imaging apparatus may be a panoramic X-ray imaging apparatus.
As the X-ray imaging apparatus is constructed as a panoramic imaging apparatus, the effect of the above-mentioned X-ray imaging apparatus can be brought out in case of panoramic imaging.
According to the X-ray imaging apparatus of the present invention, the X-ray imaging apparatus may be a cephalometric X-ray imaging apparatus.
As the X-ray imaging apparatus is constructed as a cephalometric imaging apparatus, the effect of the above-mentioned X-ray imaging apparatus can be brought out in case of cephalometric imaging.